What is the meaning of Fang Shi? When did it appear? Why did the Song Dynasty break the time?

The square system is mainly manifested in the strict separation of residential areas (squares) and trading areas (cities), and the time and place of trading are strictly controlled by laws and systems. In the Tang dynasty, the city implemented a strict system of time, separating the commercial area from the residential area, and prohibiting business in the residential area. In the Song Dynasty, the pattern of the square market was gradually broken, allowing businessmen to do business and opening shops everywhere on the street. In particular, Kaifeng, the capital of the Northern Song Dynasty, and Lin 'an, the capital of the Southern Song Dynasty, both had the largest urban population in the world at that time.